the explanation for the incorrect answer
stats:Define a method addName() in BandTag. In the doStartTag() of InstrumentTag, get a reference to BandTag through pageContext.getAncesterWithClass() and call the addName() method.
The TagSupport API does not have a findAncesterWithClass method, but it has the findAncestorWithClassfindAncesterWithClass() method is defined by TagSupport. It is not available in pageContext.
It's just a typing mistake or the method exists in another class?
Thank you
Barbara